Basic and clinical research in the biomedical sciences demands improved instrumentation for accurate measurement and reliable analysis. The objective of this research and development phase is the fabrication of a prototype two stage time-of-flight mass spectrometer based on the velocity compaction ion focusing principle. SBIR phase I results are to be used to design and build an instrument having the following characteristics: mass resolution (M/delta M fwhm) of 10,000 at mass 4,000 amu and 12,500 at mass 8,000 amu; overall flight length less than 2.00 meters; cycle repetition rate of 3-5 KHz; ion source - Cs+ ion impact for surface ionizataion of non-volatile bio-organic compounds on solid substrate; electron multiplier ion detector with fast scanning spectrum integrator; data interfaced to 16-bit based IBM-AT compatible computer with 1 megabyte RAM, dual floppy disk, 20 megabyte hard-disc and magnetic tape storage facilities. Mass calibration will be made using algorithms developed from simulated flight patterns, anchored to experimentally determined mass points. Existing software routines will be modified, expanded and converted for peak search, peak area determinations, spectrum stripping and comparison and other analytic routines.